duplicity-team team mailing list archive

[Kenneth Loafman <kenneth@xxxxxxxxxxx>]

The manifest check was in the original code I inherited.  It's the only
file verified physically against the remote, the rest are hash based.  That
verification has not caused many problems, and to my knowledge, has
detected very few comparison errors, so maybe it should just go away now.

As to hash checking on the remote, it's really not possible with the dumb
remotes we use.  We only use list/del/read/write.  Kinda minimal by design.

To answer @ede's question:  The corruption would most likely be a
truncation, not a bit flip.  As such, we would not have the hashes of the
diffdir volumes to compare against.  I've never tried to run an incremental
or a restore with the check disabled and a known corrupted manifest.  Could
be interesting to try.




On Wed, Apr 25, 2018 at 8:51 AM, edso <edgar.soldin@xxxxxx> wrote:

> On 24.04.2018 18:20, Martin Nowak wrote:
> > What's the corruption scenario that manifest comparison should protect
> against?
> >
> > The manifest contains volume checksums, but those aren't checked against
> the volumes.
>
> they should, at least during verify/restore
>
> > Eventually the remote manifest is just a copy of the local one. Multiple
> duplicity instances writing to the same remote should be ruled out as well.
>
> you never know. better safe than sorry.
>
> >
> > The only thing that seems possible is an incomplete backup, but FWIW
> duplicitly only renames a local temp manifest and uploads it to the remote
> once the full backup is done.
> >
>
> or some corruption in the backend or local file system or..
>
> what stays is the question how a corrupt manifest would affect an
> incremental or resumed backup?
> @Ken: do you want to chime in, as this smells like your area of
> expertise?
>
> additionally of course, the question still remains if this check makes
> sense there at all. obviously someone at some point thought so in the past,
> but no harm in revalidating.
>
> ..ede/duply.net
>
> --
> https://code.launchpad.net/~dawgfoto/duplicity/fixup1252/+merge/343816
> You are subscribed to branch lp:duplicity.
>

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